Recently, there have been rapidly popularized imaging devices (hereinafter, referred to merely as digital cameras), such as a digital still camera, a digital camcorder, and the like, which are capable of converting an optical image of an object into an image signal and outputting the image signal. As such digital cameras, there have been proposed many single-lens reflex camera systems (hereinafter, referred to merely as single-lens reflex cameras), each including mainly a camera body and an interchangeable lens barrel which is detachable from the camera body.
Further, in accordance with enhancement of functions of the digital camera, a microcomputer is incorporated in the interchangeable lens barrel for the single-lens reflex camera. The microcomputer operates in accordance with a program and data which are written in a ROM. For example, the microcomputer transmits data, which is specific to a lens, to the digital camera body, and controls a motor for driving the lens. The program and the data allow the single-lens reflex camera to operate optimally when a digital camera body and an interchangeable lens are combined in a manner as assumed when a camera system is designed.
However, nowadays, while a product cycle of the digital camera body has been shortened, basic performance of a lens, such as optical performance, and the like, is unlikely to become obsolete. Generally, a product cycle of the interchangeable lens barrel is longer than that of the digital camera body. Thus, there is a desire for an interchangeable lens barrel which is capable of being combined with various digital camera bodies and being used over long periods of time. However, there is a problem that unless a program and data in the interchangeable lens barrel are updated, the interchangeable lens barrel cannot be used in combination with a digital camera body having a new function, which is not assumed when a camera system is designed.
In Japanese Laid-Open Patent Publication No. 6-332691 (hereinafter, referred to as Patent Document 1), there is proposed a system incorporating therein a one-chip microcomputer realized by a microcomputer having a flash-memory. In the system disclosed in the Patent Document 1, an update program for a camera body and an interchangeable lens barrel is transmitted from a program transmitting device to the camera body. As a result, programs existing in the camera body and the interchangeable lens barrel, which is connected to the camera body through a lens mount, are replaced with the update program. As described above, in the Patent Document 1, the connection of the digital camera body to the interchangeable lens barrel allows update of the program in the interchangeable lens barrel.
Meanwhile, for enhancing the convenience of the user, there have been proposed a standard of the single-lens reflex camera system, in which a communication system between the digital camera body and the interchangeable lens barrel, a lens mount, and the like are standardized. Thus, a digital camera body and an interchangeable lens barrel, which comply with the standard, are compatible with each other, and the user can use in combination a camera body and an interchangeable lens barrel, which are manufactured by different manufacturers, for performing photographing.
[Patent Document 1] Japanese Laid-Open Patent Publication No. 6-332691